| // Copyright 2021 The Tint Authors. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #ifndef SRC_TINT_TRANSFORM_MODULE_SCOPE_VAR_TO_ENTRY_POINT_PARAM_H_ |
| #define SRC_TINT_TRANSFORM_MODULE_SCOPE_VAR_TO_ENTRY_POINT_PARAM_H_ |
| |
| #include "src/tint/transform/transform.h" |
| |
| namespace tint::transform { |
| |
| /// Move module-scope variables into the entry point as parameters. |
| /// |
| /// MSL does not allow module-scope variables to have any address space other |
| /// than `constant`. This transform moves all module-scope declarations into the |
| /// entry point function (either as parameters or function-scope variables) and |
| /// then passes them as pointer parameters to any function that references them. |
| /// |
| /// Since WGSL does not allow entry point parameters or function-scope variables |
| /// to have these address spaces, we annotate the new variable declarations |
| /// with an attribute that bypasses that validation rule. |
| /// |
| /// Before: |
| /// ``` |
| /// struct S { |
| /// f : f32; |
| /// }; |
| /// @binding(0) @group(0) |
| /// var<storage, read> s : S; |
| /// var<private> p : f32 = 2.0; |
| /// |
| /// fn foo() { |
| /// p = p + f; |
| /// } |
| /// |
| /// @compute @workgroup_size(1) |
| /// fn main() { |
| /// foo(); |
| /// } |
| /// ``` |
| /// |
| /// After: |
| /// ``` |
| /// fn foo(p : ptr<private, f32>, sptr : ptr<storage, S, read>) { |
| /// *p = *p + (*sptr).f; |
| /// } |
| /// |
| /// @compute @workgroup_size(1) |
| /// fn main(sptr : ptr<storage, S, read>) { |
| /// var<private> p : f32 = 2.0; |
| /// foo(&p, sptr); |
| /// } |
| /// ``` |
| class ModuleScopeVarToEntryPointParam final |
| : public Castable<ModuleScopeVarToEntryPointParam, Transform> { |
| public: |
| /// Constructor |
| ModuleScopeVarToEntryPointParam(); |
| /// Destructor |
| ~ModuleScopeVarToEntryPointParam() override; |
| |
| /// @copydoc Transform::Apply |
| ApplyResult Apply(const Program* program, |
| const DataMap& inputs, |
| DataMap& outputs) const override; |
| |
| private: |
| struct State; |
| }; |
| |
| } // namespace tint::transform |
| |
| #endif // SRC_TINT_TRANSFORM_MODULE_SCOPE_VAR_TO_ENTRY_POINT_PARAM_H_ |